The present invention relates to a magnetic recording/reproducing apparatus and a magnetic head equipped therein, and specifically, relates to a magnetic head for a high density magnetic recording/reproducing apparatus and a manufacturing method thereof.
A magnetoresistive magnetic head is used for a read sensor in a high density magnetic recording technology mainly composed of a hard disk and is a part which exerts a strong influence on the performance of the magnetic recording technology. Within the framework where the recording density of magnetic recording apparatus was made higher rapidly, the prior art could not achieve a magnetic recording apparatus with a sufficiently high recording density; specifically a magnetoresistive magnetic head which functions as the read element with sufficient output and sensitivity against external magnetic fields, and excellent characteristics with sufficient stability could not be obtained, so that it has been difficult to achieve the functions of a recording apparatus.
Recently, it is well known that the magnetoresistance of a multi-layered film in which ferromagnetic metal layers are stacked through a non-magnetic metal layer, a so-called giant magnetoresistance, is large. In the past, when this magnetoresistance is used for a magnetic head, a current flowing in the plane of the layered film, a so-called CIP-GMR, is used. Moreover, recently there has been research on a current-perpendicular-to-the-plane giant magnetoresistance, a so-called CPP-GMR, in which current flows in the film thickness direction of the layered film. The present invention relates to a magnetoresistive spin-valve sensor and a magnetic head using a CPP-GMR. Examples of patent references in this field include JP-A No. 204094/2003, JP-A No. 208744/2002, and JP-A No. 355682/2004.